Find the Indicated Root, or State That the Expression Is $\sqrt [ 3 ] { - 27 }$

Find the indicated root, or state that the expression is not a real number.
- $\sqrt [ 3 ] { - 27 }$

A) $- 3$
B) 3
C) not a real number
D) $- \sqrt [ 3 ] { 3 }$